Premolding article from thermoset and thermoplastic polymer dispersions

ABSTRACT

The invention is directed at new process and systems for preparing composite materials that include a polymer phase and a fiber phase.

CLAIM OF PRIORITY

The present application claims the benefit of U.S. Provisional PatentApplication No. 61/599,062 (filed on Feb. 15, 2012) which is herebyincorporated by reference in its entirety for all purposes.

BACKGROUND OF THE INVENTION

Composite materials including thermoset resins and fibers have beenemployed in manufacturing of specialty articles. The processes usingthese materials are generally labor intensive and require long curingtimes. Difficulties are also encountered when the thermoset resin ispart of a composite material that includes fibers. For example WO2010/046770 A1 describes making a polymer pre-impregnated reinforcementmaterial using solid particles, but discourages the use of thermosetresins.

The use of dispersions of thermoplastic particles for making glassfibers thermoplastics is described in International Patent ApplicationNos. WO 02/46276 and WO 99/64216. However, the authors describe thatsuch processes would not be useful with thermoset resins.

There is a desire in the pre-molding article and composite industry foran overall system of polymer matrix and fiber reinforcement which can beprocessed on a reliable basis and can be readily adoptable forhigh-volume production.

SUMMARY OF THE INVENTION

The present invention provides a pre-molding article that satisfy manyneeds of the industry.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view of an illustrative emulsion having ahigh concentration of internal phase.

FIG. 2 is an illustrative graph showing an expected relationship betweenthe apparent viscosity and the shear rate for a Newtonian fluid and fora material that exhibits shear thinning.

FIG. 3A is a cross-sectional view of an illustrative fiber architecture.

FIG. 3B is a cross-sectional view of an illustrative wet compositematerial including fibers and a dispersion of particles.

FIG. 3C is a cross-sectional view of an illustrative dry compositematerial including solid particles distributed throughout a fiberarchitecture.

FIG. 4 is a cross-section of an illustrative formed or consolidatedcomposite material after applying heat and/or pressure to a drycomposite material.

FIG. 5 is a schematic drawing illustrating processes and equipment thatmay be employed in making a wet composite material, a dry compositematerial, or a pre-molding article according to the teachings herein.

DETAILED DESCRIPTION

The technology which makes the present invention feasible is adispersion which contains a high content of solid thermoset resinparticles, and optionally solid hardeners (i.e., cross-linking agents).The dispersion has a liquid matrix phase. The liquid matrix phase mayinclude water. The low viscosity of the dispersion is leveraged to carrythe solid particles into the fibrous reinforcement architecture ofinterest. Once the particles have been dispersed throughout the fibrousarchitecture, the matrix liquid is driven off and the viscosity of thematerial system is then controlled by heat. The viscosity of the initialdispersion is generally much lower than the viscosity of the remainingdispersion ingredients once the matrix liquid has been removed. It hasbeen determined that the viscosity of the dispersion is generallyindependent of the viscosity of the polymer. The drying step may becompleted using any known means. For example, the drying stem may useheat, a dry fluid, or both.

The present invention provides that the viscosity of the dispersion maybe controlled without needing to advance the cross linking reaction oradd extra fillers as is currently done in traditional thermoset resinsystems (compositions). While prepregs are frequently mentioned, thepresent invention can be applied to all kinds of pre-molding compositesmade from fibrous reinforcement dispersion compositions.

Polymer Dispersion—Solid Phase and Liquid Phase

The polymer dispersion includes a solid phase dispersed in a liquidphase. The liquid phase includes water and/or one or more solvents. Thepolymer dispersion may be prepared using one or any combination of stepsdescribed in U.S. Pat. No. 5,539,021, U.S. Pat. No. 5,688,842, and8,063,128, and US2005/0100754A1. The polymer dispersion includes asufficient amount of the liquid phase so that the polymer dispersion canflow. The concentration of the liquid phase in the polymer dispersionmay vary from 5 weight percent, to about 35 weight percent or more,based on the total weight of the polymer dispersion. The concentrationof the liquid phase in the polymer dispersion should be sufficiently lowso that the polymer dispersion can be easily dried in one or more dryingsteps, such as a drying step that employs an elevated temperature (e.g.,a temperature of about 35° C. or more), that employs a reduce pressure(e.g., a pressure of about 0.5 atmospheres or less), or both. Theconcentration of the liquid phase in the polymer dispersion may be about85 weight percent or less, about 75 weight percent or less about 65weight percent or less, about 55 weight percent or less, about 50 weightpercent or less, or about 45 weight percent or less, based on the totalweight of the polymer dispersions. Polymer dispersions having aconcentration of liquid phase of about 45 weight percent or less areparticularly preferred so that drying times may be reduced, and/or sothat the energy costs of drying are reduced.

The amount of water in the liquid phase may be about 5% or more, about20% or more, about 30% or more, about 45% or more, about 60% or more,about 75% or more, about 90% or more, or about 95% or more, or about 99%or more, based on the total volume of the liquid phase. The amount ofwater in the liquid phase may be about 100% or less, based on the totalvolume of the liquid phase. Preferred polymer dispersions aresubstantially free of or entirely free of volatile organic solvent. Theamount of volatile organic solvent may be sufficiently low so that costs(e.g., capital costs and/or operating costs) for solvent recoverysystems may be reduced or eliminated. For example, the concentration ofvolatile organic solvents preferably is about 10 volume percent or less,about 5 volume percent or less, about 2 volume percent or less, about 1volume percent or less, about 0.5 volume percent or less, or about 0.2volume percent or less. Particularly preferred polymer dispersions arefree of volatile organic solvents in the liquid phases and the solidphase. As used herein, a volatile organic solvent may be a solventhaving a boiling point (e.g. at standard temperature and pressure) ofabout 165° C. or less, about 150° C. or less, about 135° C. or less,about 120° C. or less, about 105° C. or less, about 90° C. or less, orabout 75° C. or less.

The solid phase of the polymer dispersion includes one or more polymer.The solid phase preferably includes a sufficient amount of polymer sothat the polymer can form a matrix for the fibers of the compositematerial. The concentration of the solid phase may be about 10 volumepercent or more, about 20 volume percent or more, about 30 volumepercent or more, about 40 volume percent or more, about 50 volumepercent or more, or about 60 volume percent or more, based on the totalvolume of the polymer dispersion. The concentration of the solid phasemay be sufficiently low so that the polymer dispersion can flow and/orimpregnate the fibers. For example, the concentration of the solid phasemay be about 97 volume percent or less, about 95 volume percent or less,about 90 volume percent or less, or about 85 volume percent or less,based on the total volume of the polymer dispersion. When the polymerdispersion includes a low concentration of particles, it generally hasNewtonian flow characteristics with an apparent viscosity that isgenerally independent of the shear rate. At very high concentrations ofparticles, the polymer dispersion has flow characteristics that arecharacteristic of a shear thinning material (i.e., the apparentviscosity decreases with increasing shear rate). Although dispersions inthe shear thinning regime may be employed, the dispersion preferably hasa sufficiently low concentration of particles that it has Newtonian flowcharacteristics. At a critical concentration of particles, the materialtransitions from a Newtonian fluid to a shear thinning fluid. Thecritical concentration is typically about 55 weight percent, based onthe total weight of the polymer dispersion. The critical concentrationmay depend on any number of compositional variables, including the typeof polymer (e.g., the type of epoxy), the particle size and distributionof particle size, and the surfactant. As such, the criticalconcentration may be higher than 55 weight percent or lower than 55weight percent.

The one or more polymers of the polymer dispersion preferably includesone or more thermoset resins, one or more thermoplastic resins, or both.If more than one polymer dispersion is employed, as described herein, atleast one of the polymer dispersions preferably includes a thermosetresin.

Thermoset Polymers/Resins

The composite material includes one or more thermoset resins (i.e.,thermosetting resins). The composite material may include one or morethermoset resins that are room temperature solids, the compositematerial may include one or more thermoset resins that are roomtemperature liquids, or both. For example, the thermoset resin mayinclude a thermoset resin that is a room temperature solid and athermoset resin that is a room temperature liquid.

The thermoset resin may include, consist essentially of, or consistentirely of linear compounds. For example, the concentration of linearpolymer may be about 20 wt. % or more, about 30 wt. % or more, about 40wt. % or more, about 50 wt. % or more, about 60 wt. % or more, about 70wt. % or more, about 80 wt. % or more, about 90 wt. % or more, or about95 wt. % or more, based on the total weight of the thermoset resinsand/or based on the total weight of the polymer in the compositematerial.

A thermoset resin may be characterized as a room temperature solid. Thethermoset resin may be a glassy material having a glass transitiontemperature of of about 10° C. or more, of about 20° C. or more, ofabout 30° C. or more, of about 40° C. or more, of about 50° C. or more,or of about 60° C. Preferably the thermoset resin has a sufficiently lowglass transition temperature so that it can be processed at temperaturesof about 120° C. or less. For example, the thermoset resin may have aglass transition temperature of about 120° C. or less, about 110° C. orless, about 100° C. or less, about 90° C. or less, or about 80° C. orless. The thermoset resin may be a semi-crystalline resin having amelting temperature of about 30° C. to about 270° C. (e.g., from about30° C. to about 120° C.). Preferably, the one or more thermoset resinsincludes, consists essentially of, or consists entirely of glassymaterials having a glass transition temperature greater than 25° C.Preferably, the one or more thermoset resins is substantially free of,or entirely free of semi-crystalline resins. If present, theconcentration of thermoset resins that are crystalline is preferablyabout 29 wt. % or less, about 19 wt. % or less, about 9 wt. % or less,or about 4 wt. % or less, based on the total weight of the thermosetresin or based on the total weight of the polymer in the compositematerial.

The molecular weight of the thermoset resin that is a room temperaturessolid (i.e., solid thermoset resin) may be sufficiently high so that thethermoset resin has a glass transition temperature of about 30° C. ormore, about 40° C. or more, about 50° C. or more, or about 60° C. ormore. When the composition includes both solid and liquid thermosetresins, the solid thermoset resin preferably has a relatively highmolecular weight compared with the liquid thermoset resin, where themolecular weight is the number average molecular weight of the resin.For example, the ratio of the molecular weight (e.g., number averagemolecular weight) of the solid thermoset resin to the molecular weightof the liquid thermoset resin may be about 1.1 or more, about 1.4 ormore, about 1.8 or more, about 2.4 or more, about 3 or more, or about4.5 or more. Preferred solid thermoset resins have an epoxide equivalentweight of about 400 or more, about 600 or more, about 1000 or more, orabout 1500 or more. The solid thermoset resin preferably has an epoxideequivalent weight of about 14000 or less, about 6000 or less, about 4000or less, or about 2500 or less. Preferred solid thermoset resins have anumber average molecular weight of about 800 daltons or more, about 1200daltons or more, about 2000 daltons or more, or about 3000 daltons ormore. The solid thermoset resin preferably has a number averagemolecular weight of about 28000 or less, about 12000 or less, about 8000or less, or about 5000 or less. When the polymer dispersions includesboth a liquid and a solid thermoset resin (e.g., both a solid epoxyresin and a liquid epoxy resin), the weight ratio of the solid thermosetresin to the liquid thermoset resin preferably is sufficiently high sothat the material is tack free at about 25° C. The weight ratio of thesolid thermoset resin to the liquid thermoset resin may be about 0.2 ormore, about 0.4 or more, about 0.6 or more, or about 0.8 or more. Theweight ratio of the solid thermoset resin to the liquid thermoset resinpreferably is sufficiently low so that two pieces of the dry compositematerial can more easily be attached by heating the surface at least oneof the pieces. The weight ratio of the solid thermoset resin to theliquid thermoset resin may be about 20 or less, about 10 or less, about5 or less, about 3 or less, or about 2 or less. Compositions that aresubstantially free of, or entirely free of liquid thermoset resin (e.g.,free of liquid epoxy resin), may also be used in the compositionsaccording to the teachings herein.

A thermoset resin may be characterized as a room temperature liquid(i.e., a liquid thermoset resin). For example, the thermoset resin maybe a liquid material having a glass transition temperature of less than25° C., of about 20° C. or less, of about 10° C. or less. The glasstransition temperature of the liquid thermoset resin may be about −60°C. or more, about −50° C. or more, about −30° C. or more, or about −10°C. or more. If the glass transition temperature is too low, thethermoset resin may flow out of the mold, may be difficult to handle(e.g., due to tack), may require long cure times, or any combinationthereof.

The thermoset resin may include one or any combination of the thermosetresins described in U.S. Pat. No. 5,539,025 (col. 8, line 66 to col. 9,line 62) and/or one or more of the thermoset resins described in WO2009/074293 pages 3, line 31 to page 5, line 2. The thermoset resin mayinclude one or more epoxies, one or more phenolics, one or morepolyesters, one or more acrylates, one or more polymides, one or morepolyimides, or any combination thereof. Preferably the thermoset resinincludes, consists essentially of, or consists entirely of one or moreepoxy resins.

Epoxy Resin

The epoxy resin may be a product of polymerization reaction involving anepoxide containing monomer. The epoxide containing monomer may includeone or more, or two or more epoxide groups. Some or all of the epoxidegroups of the epoxide containing monomer may be terminal epoxide groups.For example, the epoxide group may include one or more (e.g., two ormore) terminal epoxide groups. The polymerization reaction may be ahomopolymerization or may be a copolymerization reaction. For example,the epoxide containing monomer may be copolymerized with one or moresecond monomers, such as a second monomer that reacts with an epoxidegroup.

The epoxy resin may be include one or more flexibilizing agents or maybe free of flexibilizing agents. If employed, the flexibilizing agentmay be copolymerized with the epoxide containing monomer, or a separatephase. Preferably the concentration of flexibilizing agent is about 29wt. % or less, more preferably about 19 wt. % or less, even morepreferably about 9 wt. % or less based on the total weight of thepolymer in the composite material. The epoxy may include an epoxydescribed in U.S. Pat. No. 5,539,025 column 6, line 9 to column 7, line2) or an epoxy resin described in WO 2009/074293 pages 5, lines 26-33.Without limitation, the epoxy resin may include one or any combinationof the following: an aliphatic glycol based epoxy resin, a bisphenol Abased epoxy resin (e.g., bisphenol A+epichloohydrin), a diglycidyl etherof bisphenol A (DGEBA), a novolac based epoxy resin, or a brominatedepoxy resin.

Hardener/Curative Catalyst

The dispersion may include one or more cross-linking agents (i.e.,hardener) suitable for reacting with the thermoset resin. Thecomposition may also include one or more curative catalysts suitable foraccelerating the rate of the cross-linking reaction. The cross-linkingagent and/or the curative catalyst may be encapsulated. Thecross-linking agent and/or the curative catalyst may be in a particlephase, such as a particle phase including a solid thermoset resin, aparticle including a liquid thermoset resin, a particle including athermoplastic resin, or any combination thereof. The cross-linking agentand/or the curative catalyst may be soluble in the liquid matrix phaseof the dispersion. Preferably, one or both of the cross-linking agentand the curative catalyst are not in some or all of the particles thatcontain the solid thermoset resin. It will be appreciated that thecross-linking agent and/or the curative catalyst may be provided to thefibers separately from the dispersion. For example, the process mayinclude a separate step of coating or otherwise contacting the fiberswith the cross-linking agent, with the curative catalyst, or both, priorto contacting the fibers with the dispersion.

The cross-linking agent may react with one or more of functional sitesof the thermoset resin. The thermoset resin, the cross-linking agent, orboth may be a compound having a sufficiently high functionality so thata network structure is formed. The Functionality of a compound (e.g., athermoset resin or a cross-linking agent) describes the number ofreactive sites on the compound that may be employed in a crosslinkingreaction, such as a chemical cross-linking reaction used for curing thethermoset resin. For example, a resin having 2 terminal reactive epoxidegroups has a functionality of 2. As another example, a diamine includingtwo terminal —NH₂ groups has a functionality of 4. The cross-linkingreaction may employ a step of reacting a functional group of thethermoset resin with a functional group of the cross-linking agent.

The cross-linking agent and/or curative catalyst are preferably selectedand present in a sufficient quantity so that the thermoset resin rapidlycross-links when heated in the molding process according to theteachings herein.

The cross-linking reaction may be evaluated at one or more of thefollowing curing temperatures, Tc: about 100° C., about 110° C., about120° C., about 130° C., about 140° C., or about 150° C. and at one ormore of the following target curing times: about 10 minutes, about 5minutes, about 3 minutes, about 2 minutes, about 1 minute, or about 30seconds. The cross-linking agent and/or curative catalyst are preferablyselected and present in a sufficient quantity so that after reacting forthe target cure time, the thermoset resin achieves a glass transitiontemperature equal to or greater than Tc−10° C., more preferably equal toor greater than −5° C. or more, even more preferably equal to or greaterthan Tc, even more preferably equal to or greater than Tc+5° C., evenmore preferably equal to or greater than Tc+10° C., and most preferablyequal to or greater than Tc+15° C. The glass transition temperature onthe cured material is measured using dynamic mechanical thermal analysis(DMTA). Dynamic mechanical thermal analysis (DMTA) is performed using aTA Instruments ARES G2 rheometer. Specimens are cut from the compositematerial. The specimen may be cut from the same panels which are used toobtain specimens for flexural modulus testing. The DMTA specimens have arectangular geometry with dimensions of 1.75″×0.5″ (length×width) andare cut to dimension using a wet circular mechanical saw. The specimenis loaded onto a torsion rectangular sample fixture at 30° C. Duringtesting, small-amplitude oscillatory shear experimental conditions areemployed, including a fixed oscillation frequency of 1 Hz and a strainamplitude of 2%. A temperature ramp from 30 to 220° C. at 3° C./min isemployed. Nitrogen is imposed on the sample and the temperature iscontrolled with a forced-air temperature controller.

The amount of the hardener in the composition is preferably about 0.4 ormore, more preferably about 0.5 or more, more preferably about 0.6 ormore, and most preferably about 0.7 or more equivalents with respect tothe active hydrogen equivalents of all of the epoxy groups in thecomposition. The amount of the hardener in the composition is preferablyabout 3.0 or less, more preferably about 2.0 or less, even morepreferably about 1.6 or less, even more preferably about 1.4 or less,and most preferably about 1.3 or less equivalents with respect to theactive hydrogen equivalent of all of the epoxy groups in thecomposition. The amount of the hardener component in the composition ispreferably about 1 part or more, more preferably about 2 parts or more,even more preferably about 3 parts or more, and most preferably about 4parts or more, by weight, based on the total parts of epoxy resin in thecomposition. The amount of the hardener component is preferably about 25parts or less, more preferably about 20 parts or less, even morepreferably about 15 parts or less, and most preferably about 10 parts orless, by weight, based on the total weight of the one or more epoxyresins in the composition.

The composition may optionally include one or more cure acceleratorssuitable for increasing the rate of curing the thermoset resin, suitablefor increasing the glass transition temperature of the cured thermosetresin, or both.

The dispersion particles may optionally include one or polymer modifierssuitable for improving the mechanical properties of the thermoset resin.For example, the polymer modier may increase the impact propertiesand/or the tensile elongation (e.g., the elongation at failure) of thecured thermoset resin. Some modifiers may additionally function as across-linking agent.

The composition of the polymers in the present invention furthercomprises one or more thermoplastic resins. The use of a thermoplasticresin may take advantage of one or any combination of the followingcharacteristics possible in a thermoplastic (e.g., compared with thethermoset resin) including relatively high toughness, relatively highfatigue resistance, ability to fuse or join (e.g., by melting thethermoplastic), relatively good storage stability (e.g., relativelyconstant viscosity over time), and relatively easy to reprocess and/orrepair. Preferably the thermoset resin, the thermoplastic resin and thecuring compounds (i.e., any cross-linking agent and any cross-linkingaccelerator) are not all provided in the same particles. For example,the particles including the thermoset resin may be free of both thethermoplastic resin and the curing compounds, or may include only of thethermoplastic resin and the curing compounds. The thermoplastic resin,preferably is provided in a thermoplastic resin dispersion (i.e., inseparate particles from the thermoset resin particles).

The thermoplastic resin may include one or more homopolymers, one ormore copolymers, or both. Examples of thermoplastic resin that may beemployed include polyolefins, polybutylene terephthalates,acrylonitrile-butadiene-sytrene copolymers (ABS), polyamides,polyethylene terephthalates, polymethacrylates, polyvinyl acetal resins,polyvinyl acetates, polyacetal, polyphenylene sulfides, polyethersulfones, phenoxy resins, or any combination thereof. The thermoplasticresin may include one or more polymers suitable for toughening thethermoset resin so that the impact strength is increased. Particularlypreferred tougheners include polymers having rubbers, copolymers, orboth. For example, the toughener may include a butadiene-acrylonitrilecopolymer, a carboxyl-modified butadiene-acrylonitrile copolymer, coreshell polymers including rubber particles, an acrylate copolymer.Preferred acrylate copolymers include copolymers include one or more(e.g., two or more) monomers selected from the group consisting ofacrylate, methacrylate, methyl methacrylate, and butyl acrylate. Thetoughener may include, consist essentially of, or entirely of PARALOID®EXL-2611 or PARAOLOID® XL-3387 (commercially available from Rohm & Haas)comprising a butyl acrylate-methyl methacrylate copolymer.

Preferred polyolefins include, consist essentially of, or consistentirely of one or more olefin monomers having 2 to 20 carbon atoms. Thepolyolefin may be a homopolymer a olefin monomer at a concentration ofabout 98 weight percent or more, more preferably about 99 weight percentor more, and most preferably about 99.5 weight percent or more (e.g.,about 100 weight percent), based on the total weight of the polyolefin.The polyolefin may be a copolymer including a first olefin monomer andone or more second monomers. The one or more second monomers may includeone or more olefins olefin, one or more non-olefinic monomers, or both.The first olefin monomer preferably is present at a concentration ofabout 50 weight percent or more, more preferably about 60 weight percentor more, even more preferably about 70 weight percent or more, even morepreferably about 80 weight percent or more, and most preferably about 85weight percent or more, based on the total weight of the polyolefin.Preferably the first olefin is ethylene, propylene, 1-butene, or1-hexene. Preferably, the second monomer includes or consistsessentially of one or more monomers selected from the group consistingof ethylene, propylene, 1-butene, 1-hexene, 1-octene, vinyl acetate,butyl acrylate, methyl methacrylate, styrene, acrylic acid, and methylacrylate, with the proviso that the second monomer is different from thefirst olefin. The second monomer may consist of one or more olefins.Preferably the total concentration of the first olefin and the secondmonomer (e.g., one or more second monomers listed above) is about 90weight percent or more, more preferably about 95 weight percent or more,and most preferably about 99 weight percent or more. Particularlypreferred polyolefins that may be employed include polypropylenehomopolymers, polypropylene copolymers, polyethylene homopolymers, andpolyethylene copolymers. Other particularly preferred polyolefinsinclude copolymers of ethylene, propylene, or both, with one or morepolar monomers.

Preferred polyesters include polyethylene terephthalate, polybutyleneterephthalate, and copolymers thereof.

Polyamides generally are polymers having one or more repeating unitsthat includes an amide groups along the backbone of the polymer chain.For example, polyamides may be a reaction products of a diamine and adiacid. Other examples of polyamides include monadic polyamides.Generally, monadic polyamides are formed by a ring opening reaction.Exemplary polyamides which are formed from a diamine and a diacid mayinclude polyamides (e.g., polyamides) containing reaction products ofeither adipic acid or terephthalic acid with a diamine. Exemplarymonadic polyamides include polyamide 6, and poly(p-benzamide). Thepolyamide may be a homopolymer, a copolymer, or a mixture thereof.Preferred polyamide homopolymers which may be used in the presentinvention include polyamide 3, polyamide 4, polyamide 5, polyamide 6,polyamide 6T, polyamide 66, polyamide 610, polyamide 612, polyamide 69,polyamide 7, polyamide 77, polyamide 8, polyamide 9, polyamide 10,polyamide 11, polyamide 12, and polyamide 91. Copolymers containing anyof the above mentioned polyamides may also be used. Polyamide copolymersmay be random copolymers, block copolymers, a combination thereof.Examples of polyamide copolymers include polymers having a plurality ofdifferent amides (i.e., a polyamide-polyamide copolymers),polyesteramide copolymers, polyetheresteramide copolymers,polycarbonate-ester amides, or any combination thereof.

The dispersion, the composite, or both may include one or morecompatibilizers suitable for compatibilizing the thermoset resin and thethermoplastic resin. Preferred compatibilizers react with the thermosetresin and/or the thermoplastic polymer to produce a covalent bond. Forexample, the compatibilizer may result in covalent bond between thethermoplastic polymer and the thermoset resin.

Preferred thermoplastic polymers have a solid to liquid phase transitionof about 70° C. or more, about 100° C. or more, about 130° C. or more,or about 150° C. or more. The thermoplastic polymer preferably has asolid to liquid phase transition of about 280° C. or less, about 220° C.or less, or about 180° C. or less. The solid to liquid phase transitionmay be a glass transition temperature, or a final melting temperature,both of which can be measured using differential scanning calorimetry bymelting the thermoplastic polymer, then cooling at a rate of 10° C./minto 0° C. and then determining the transition temperature upon reheatingthe thermoplastic polymer at a rate of 10° C./min.

The dispersion may include one or more surfactants suitable for makingan emulsion of the one or more ingredients that are in a dispersionparticle. For example, the dispersion may include a surfactant suitablefor making an emulsion of the thermoset resin. Similarly, the dispersionmay include a surfactant suitable for making an emulsion of a hardener.Any art known surfactant may be employed. The surfactant may be acationic surfactant, an anionic surfactant or a nonionic surfactant. Thesurfactant may include one or any combination of the surfactantsdescribed in U.S. Pat. No. 5,539,025 (Issued on Jul. 23, 1996) column 6,line 9 to column 7, line 2) and/or one or more of the surfactantsdescribed in International Patent Application Publication WO 2009/074293(published on Jun. 18, 2009) pages 5, lines 26-33.

The composite material includes one or more fibrous materials suitablefor reinforcing the composite material. The fibers may be in any form.For example, the fibers may include: short fibers, long fibers,non-woven fibers, woven fibers, or any combination thereof. The fibersmay be unidirectional fibers. The fibers may be oriented in a pluralityof directions. For example one fiber may be oriented in a firstdirection and a second fiber may be oriented in a second directionhaving a predetermined angle from the first direction. The fibers may berandomly oriented in two or more dimensions. For example, the fibers maybe randomly oriented short fibers. The fibers may include organicfibers, inorganic fibers or both. An organic fiber may be a polymericfiber, such as an aramid fiber. Examples of inorganic fibers that may beemployed include carbon fibers, glass fibers, silicon carbide fibers. Aparticularly preferred fiber is a carbon fiber. The fiber preferably isa reinforcing fiber suitable for increase the stiffness and/or strengthof the composite material. Preferred fibers are generally stiff ascharacterized by a high tensile modulus. For example, the fibers mayhave a tensile modulus of about 20 GPa or more, about 50 GPa or more,about 100 GPa or more, about 150 GPa or more, or about 200 GPa or more.The fibers may have a tensile modulus of about 500 GPa or less, or about300 GPa or less.

The composition should have a sufficient amount of the thermoplasticresin so that the pre-molding article has one or more characteristics ofa thermoplastic resin. The weight ratio of the thermoplastic resin tothe thermoset resin preferably is about 0.1 or more, more preferablyabout 0.2 or more, even more preferably about 0.4 or more, and mostpreferably about 0.6 or more. The compositions preferably has asufficient amount of the thermoset resin so that the pre-molding articlehas one or more of the characteristics of a thermoset resin. Forexample, the weight ratio of the thermoplastic resin to the thermosetresin preferably is about 10 or less, more preferably about 5 or less,even more preferably about 2.5 or less, and most preferably about 1.6 orless.

The concentration of the fibers should be sufficiently high so that thefibers can provide the desired reinforcing properties to the compositematerial. The concentration of fibers is preferably about 25 weightpercent or more, more preferably about 35 weight percent or more, evenmore preferably about 45 weight percent or more, and most preferablyabout 52 weight percent or more, based on the total weight of the drycomposite material. The concentration of fibers is preferablysufficiently low so that the dispersion particles can flow between thefibers and/or so that a high bulk density (e.g., compared to the fiberswithout the thermoset material) can be achieved. The concentration ofthe fibers preferably is about 85 weight percent or less, morepreferably about 78 weight percent or less, even more preferably about70 weight percent or less, even more preferably about 66 weight percentor less, and most preferably about 62 weight percent or less, based onthe total weight of the dry composite material.

Optionally, the dry composite material, the dispersion, or both mayinclude an internal mold release agent. The mold release agent may beselected so that any force required to remove the molded part from amold die is reduced or eliminated. The mold release agent may allow forincreasing the molding temperature by making it easier to remove thecured material from the mold. Examples of internal mold release agentsthat may be employed include waxes, silicones, fluoropolymers,surfactants, fatty acids, fatty acid esters, or any combination thereof.

The ratio of the volume of the thermoset resin to the volume of thefibers is preferably about 0.05 or more, more preferably about 0.10 ormore, even more preferably about 0.20 or more, and most preferably about0.3 or more. The volume ratio of the thermoset resin and the fibers ispreferably about 5 or less, more preferably about 2.5 or less, even morepreferably about 1.5 or less, and most preferably about 1 or less.

The ratio of the weight of the thermoset resin in the dispersion to theweight of the matrix liquid phase of the dispersion preferably is about0.1 or more, more preferably about 0.3 or more, even more preferablyabout 0.6 or more, even more preferably about 1.0 or more, and mostpreferably about 1.2 or more. The ratio of the weight of the thermosetresin to the weight of the matrix liquid phase of the dispersionpreferably is about 10 or less, more preferably about 8 or less, evenmore preferably about 6 or less, even more preferably about 5 or less,and most preferably about 4 or less.

The total weight of the fibers, thermoset resin, thermoplastic resin,curative, cure catalyst, and the internal mold release agent, preferablyis about 50 weight % or more, more preferably about 60 weight % or more,even more preferably about 70 weight % or more, even more preferablyabout 80 weight % or more, even more preferably about 90 percent % ormore, even more preferably about 95 weight % or more, and mostpreferably about 99 weight % or more based on the total weight of thedry composite material.

While the present invention has broad applicability in many compositesmaking processes, listed below are three exemplary categories ofprocesses:

Preparation of Emulsion/Dispersion

The process may include one or more steps of preparing a dispersion,such as an aqueous dispersion. According to the teachings herein, adispersion may include, consist essentially of, or consist entirely ofone or any combination of the following: a continuous liquid phase, oneor more thermoset resins, one or more surfactants, one or more moldrelease agents, one or more catalysts, or one or more curatives. Theprocess may include a dispersion (e.g., a dispersion mixture) thatincludes a step of mixing or otherwise combining a plurality ofdispersions. Generally, at least one dispersions includes a thermosetresin. When a plurality of thermoset resins are employed (such as twothermoset resins having different initial glass transition temperatures)two or more thermoset resins may be included in a single dispersionparticle. Alternatively, the dispersion may be a dispersion mixtureincluding a first dispersion particle including thermoset resin and asecond dispersion particle including thermoset resin, where the firstand second dispersion particle have different concentrations of the twothermoset resins. For example, the dispersion particles may becharacterized by one or any combination of the following features: theconcentrations of the first thermoset resin in the first and seconddispersion particle are different (e.g., by about 5 wt. % or more, or byabout 10 wt. % or more); the concentrations of the second thermosetresin in the first and second dispersion particles are different (e.g.,by about 5 wt. % or more, or by about 10 wt. % or more); the ratio ofthe concentrations of the first and second thermoset resins aredifferent in the two dispersion particles (e.g., the ratio of the twoconcentration ratios is about 0.8 or less or 1.25 or more). For example,i) a first dispersion particle may include the first thermoset resin andbe free of the second thermoset resin and/or ii) a second dispersionparticle may include the second thermoset resin and be free of the firstthermoset resin.

The use of dispersions provide the advantage of being able to easilytailor the composition of the matrix material (i.e., the material thatremains in the matrix of the composite after the water is removed). Acomposition can be tailored using a mixture of different dispersions.For example, the composition may be formed from a mixture of two or more(e.g., three or more, or even all) of the following: a dispersion ofcurative particles in water, a dispersion of a solid thermoset resin inwater, a dispersion of a non-solid thermoset resin in water (e.g., aliquid thermoset resin), a dispersion of a toughener in water, adispersion of a mold releasing agent in water, or a dispersion of across-linking accelerator in water. Particles of any of these materialscan be employed without concern that the viscosity of the dispersionmixture will be affected by the flow characteristics of the individualingredients.

The process may include one or more steps of preparing a dispersion,such as an aqueous dispersion The dispersion may be made by anyconvenient method suitable for providing a dispersion of particles in aliquid having one or more of the features according to the teachingsherein. Preferred processes result in dispersion particles that aresufficiently small so that they can flow enter and/or flow through thespaces formed between fiber particles, such as the spacing betweenfibers in a mat or in a bundle of fiber strands. The process forpreparing a dispersion may include an emulsifying process. For example,a liquid component of the composition to be cured (i.e., of the drycomposite material) may be prepared as an emulsion in water using aprocess that employs mixing and/or surfactant(s) for achieving agenerally stable emulsion. An emulsifying process may also be employedwith solid components of the composition. For example, the process mayinclude a step of heating a solid component so that it becomes a liquidsuitable for an emulsifying process. Upon cooling, such an emulsionparticle may solidify so that a solid dispersion particle is formed. Theprocess of preparing a dispersion may include mixing two or morecomponents of the composition prior to making the dispersion. Theprocess may include a step of emulsifying two components of thecomposition in different emulsifying step. The dispersion process mayinclude one or any combination of the features described in PCT PatentApplication Publication Numbers WO99/64216 (published on Dec. 16, 1999,see e.g. page 4, line 5 to page 15, line 28), WO02/46276A2 (published onJun. 13, 2002), and WO 2011/064176A1 (published on Jun. 3, 2011, seee.g. page 3, line 1 to page 11, line 2); U.S. Pat. No. 3,879,324 issuedon Apr. 22, 1975 (see e.g. column 1, line 63 to column 6, line 29), U.S.Pat. No. 3,993,843 issued on Nov. 23, 1976, U.S. Pat. No. 4,315,044issued on Feb. 9, 1982 (see e.g., column 1 lines 8 to column 6, line30), U.S. Pat. No. 4,222,918 issued Sep. 16, 1980, U.S. Pat. No.4,886,485 issued on Dec. 12, 1989 (see e.g., col. 2, line 15 to column9, line 48) U.S. Pat. No. 5,539,025 issued on Jul. 23, 1996 (see e.g.column 1, line 58 to column 2, line 24, and column 5 line 37 to column12, line 57), U.S. Pat. No. 6,147,131 issued on Nov. 14, 2000 (see e.g.column 7, lines 4-16), and U.S. Pat. No. 5,688,842 (see e.g. column 3line 39 to column 8, line 16); European Patent Application No. EP 1 266920 B1 (published on Dec. 18, 2002), all incorporated herein byreference in their entireties. The process may include a step ofpreparing a high internal phase emulsion (HIPE) such as described inU.S. Pat. Nos. 4,018,426, 4,522,953, 5,198,472 and 5,210,104, allincorporated herein by reference in their entireties. An emulsificationprocess may employ a batch process for preparing the emulsion or acontinuous process for preparing the emulsion. By way of example, theprocess may include a step of gradually adding water into a mixtureincluding the component(s) to be emulsified (e.g., a thermoset resin ina liquid state) and a surfactant, preferably while the mixture is beingagitated. Agitation can be accomplished by any suitable means, such aswith an agitator including one or more impellers. As another example,the process may include a step of mixing a first continuous stream ofwater with a second continuous stream including the liquid component(s)to be emulsified and a surfactant, using sufficient shear so thatemulsion particles are formed. It will be appreciated that particles maybe made by process other than by an emulsion process. For example, adispersion particle may be made by an encapsulation process. Anencapsulation process may be used to encapsulate one or more ingredients(e.g., in the same particle or in different particles). Such anencapsulation process may be particularly useful for encapsulating acurative (i.e., a hardener), a cure catalyst (i.e., a cross-linkingcatalyst), or both. For example, the dispersion may include particlescontaining epoxy resin and particles containing a hardener, wherein theepoxy resin particles are encapsulated, the hardener particles areencapsulated, or both. An encapsulation process may be used toencapsulate one or more ingredients (e.g., in the same particle or indifferent particles). Such an encapsulation process may be particularlyuseful for encapsulating a curative (i.e., a hardener), a cure catalyst(i.e., a cross-linking catalyst), or both. For example, the dispersionmay include particles containing epoxy resin and particles containing ahardener, wherein the epoxy resin particles are encapsulated, thehardener particles are encapsulated, or both. An encapsulated ingredientmay be particularly useful for preventing reaction between an ingredientwithin the encapsulated particle and an ingredient exterior to theencapsulated particle, until a predetermined triggering condition isreached. The triggering condition may be heat, pressure, exposure to IRradiation, exposure to UV light, exposure to microvaves, or anycombination thereof. For example, the triggering condition may be asufficient amount of heat so that a critical temperature is reached(e.g., a temperature at which the encapsulating material melts orsoftens).

A dispersion particle may include a cross-linking agent, a cross-linkingcatalyst, or both. For some curing systems, it may be preferable for adispersion particle, such as a dispersion particle including thermosetresin, to be substantially free of a cross-linking agent, to besubstantially free of a cross-linking catalyst, or to be substantiallyfree of both cross-linking agent and cross-linking catalyst.

The process may include combining two or more dispersions. For example,the process may include combining two or more different soliddispersion, the process may include combining one or more soliddispersion and one or more emulsions, or both. By employing a pluralityof different dispersion, it may be possible to use a group ofdispersions for preparing different compositions having differentcomponents and/or having different concentrations of one or morecomponent. Preferably all of the ingredients to be mixed with orotherwise dispersed into the fibers are included in a dispersion mixturethat includes generally identical dispersion particles or a plurality ofdifferent dispersion particles. A dispersion, a dispersion mixture, orboth may have a predetermined concentration of one or any combination ofthe following ingredients: water, resins (e.g., thermoset resins and/orthermoplastic resins), curative, catalyst, mold release agent, orsurfactant).

One or more of the ingredients may be water soluble. For example, thecatalyst, mold release agent, the curative, or both may be watersoluble. Some or all of the water soluble component may be substantiallyor entirely excluded from some or all of the particles of the dispersionmixture.

The process may include adjusting the amount of water in the dispersionmixture. For example, water may be added to a solid dispersion, to anemulsion, to a dispersion mixture, or any combination thereof.Similarly, water may be removed from one or more dispersions or from amixture of dispersions (e.g., prior to contacting with the fibers). Itwill be appreciated that the flow characteristics of a dispersion or adispersion mixture may be controlled by adjusting the waterconcentration.

Preferably, the temperature, mixing conditions and surfactant(s)employed in the process for preparing the dispersion are selected sothat the dispersion particles have a diameter less than thepredetermined maximum dispersion particle diameter limit. The ratio ofthe predetermined maximum dispersion particle diameter limit to thediameter of the fibers may be about 1.00 or less, preferably about 0.70or less, more preferably about 0.50 or less, even more preferably about0.30 or less, even more preferably about 0.24 or less, even morepreferably about 0.10 or less and most preferably about 0.04 or less. Byway of example, the dispersion, the dispersion may be employed withfibers having a diameter of about 40 μm and the dispersion particlessize may be about 40 μm or less, about 28 μm or less, about 20 μm orless, about 12 μm or less, about 9.6 μm or less, about 4 μm or less, orabout 0.96 μm or less. For use with a wide range of fiber diameters, itis preferred that the dispersion particles have a low diameter.Preferred the average diameter of the dispersion particles, the maximumdiameter of the dispersion particles, or both is about 5 μm or less,more preferably about 2 μm or less, even more preferably about 1 μm orless, even more preferably about 0.8 μm or less, and most preferablyabout 0.6 μm or less. Typically, the dispersion particles have adiameter of about 0.1 μm or more; however particles having a diameterless than 0.1 μm can generally be employed.

Preferred dispersions have a sufficiently low viscosity so that they canflow into an architecture of fibers. For example, the dispersionpreferably has a viscosity (at 25° C.) of about 50,000 cps or less, morepreferably 10,000 cps or less, and most preferably about 3,000 cps orless.

Preparing the Wet Composite Material

The process includes steps of combining the dispersion mixture and thefibers, so that a wet composite material including the dispersionmixture and fibers is formed. For example, the process may include oneor any combination of the following steps: i) contacting the dispersionmixture (including dispersion particles and water) with one or morestrands of fiber, ii) contacting the dispersion mixture with a pluralityof fiber particles; or iii) contacting the dispersion mixture with a matof fibers (e.g., woven fibers, non-woven fibers, or both). A processincluding the step of contacting the dispersion mixture with one or morestrands of fibers may include one or more art known steps employed indirect long fiber thermoplastic processes in which strands of fibers arecoated with a polymer. A process including a step of contacting adispersion mixture with a plurality of fiber particles may include oneor more art known steps employed in preparing sheet molding compoundsincluding fiber particles. A process including a step of contacting thedispersion mixture with a mat of fibers may include one or more artknown steps employed in making a thermoset/fiber prepreg. Some or all ofthe dispersion particles includes a thermoset resin. Preferably thedispersion mixture includes a cross-linking agent and a catalyst foraccelerating the cross-linking reaction. The cross-linking agent and thecatalyst may be soluble in the water, may be present in some or all ofthe dispersion particles, or both.

Sheet Molding Compound

The process of contacting the fibers and the dispersion may be used in aprocess for making a sheet molding compound that includes reinforcingfibers. Advantageously, a sheet molding compound prepared according tothe teachings may be prepared in a process that is free of a maturationstep to control the viscosity, that is free of a step of addingadditional fillers (e.g., non-fibrous fillers, such as non-fibrousmineral fillers) to control the viscosity, or both. For example, theprocess may be free of a maturation step that increases the cross-linkdensity or the glass transition temperature of the resin. Prior to thepresent invention, in typical sheet (composite) molding compound resins,mineral fillers such as calcium carbonate are added to increaseviscosity. Prior to the present invention, after the composite is formedby molding, the composite requires a maturation step which involvesapplying heat to advance the composite and begin to increase the crosslink density. This increase in cross link density significantlyincreases the material system viscosity, which in turn enables thepre-molding composite to have enough structure to be handled and placedinto a mold for another (e.g., a final) compression molding step. In thepresent invention, the dispersion has a relatively low viscosity,typically around 1000 cps) compared with the viscosity of the thermosetresin and/or other ingredients in the dispersion. For example, the ratioof the viscosity (e.g., the zero shear viscosity) of the thermoset resinto the viscosity of the dispersion may be about 2 or more, about 10 ormore, about 100 or more, or about 1000 or more. The thermoset resin mayeven be a solid (i.e., having essentially an infinite viscosity at roomtemperature). As such, the aqueous phase of the dispersion allows forthe ease of infusing and mixing a fibrous material used forreinforcement with a thermoset resin having a generally high viscosity,such as a solid thermoset resin. In contrast, the prior art generallyrequires that the thermoset resin be in a solid state when mixed withthe fibers. As discussed herein, the fibrous material for the sheetmolding compound may be in any form, such as short fiber, woven fibers,or unidirectional fibers. After contacting the dispersion and thefibers, the wet composite material may be processed into a sheet orother shape suitable for a sheet molding operation, for example bycasting, filming, extruding, or pouring onto a flat substrate (e.g., aflat release substrate). Before using the composite material (e.g., in asheet form) in a sheet molding operation, it may be desirable toincrease the viscosity of the wet composite material. In order toincrease the viscosity of the pre-molding composite, the some or all ofthe aqueous portion of the wet composite material may be removed using adrying step to form a dry composite sheet. For example, the drycomposited sheet may consist substantially of solids including thefibers and solid resin (e.g., the solid thermoset resin). Preferably theconcentration of solids in the dry composite sheet is about 50 volumepercent or more, more preferably about 70 volume percent or more, evenmore preferably about 80 volume percent or more, and most preferablyabout 90 volume percent or more, based on the total volume of the sheet.It will be appreciated that the sheet may include some liquid material,such as a liquid resin. For example, the sheet may include a liquidphase thermoset resin, such as a liquid epoxy resin. Small amounts ofsuch resins may be sufficient for serving as a binder for bindingtogether two solid resin particles, for binding together a solidparticle and a fiber, or both. The apparent viscosity of the drycomposite material (i.e., the dehydrated material system) may be veryhigh, and may be incapable of flowing at room temperature. However, thedry composite material preferably is still formable after heating. Forexample, the dry composite material may be formable after heating to atemperature greater than the glass transition temperature of thethermoset resin. The dry composite sheet may be used in a traditionalSMC (sheet molding compound) compression molding process. Such a processpreferably employs a sufficient amount of heat to soften the thermosetresin for shaping into a part and to rapidly cure the shaped part. Forexample, the temperature may be sufficiently high so that the part iscured in about 10 minutes or less, about 5 minutes or less, about 3minutes or less, about 2 minutes or less, or about 1 minute or less. SMCcompression molding process preferably employs a sufficient amount ofpressure for achieving a desired shape. As such, this process eliminatesthe maturation step typically required in traditional SMC materialstoday. In the present invention, heat and water content are thepreferred control mechanisms used to control the viscosity of thedispersion, and the composite made using the dispersion may thus includepolymer having a relatively high viscosity, as opposed to prior SMCsystems that require starting with relatively low viscosity thermosetpolymers and adding fillers or advancing the cross linking reaction asis done in traditional thermosetting material systems. Because extrafillers are not needed, the additional benefits of improved strength andductility in the present system are obtained.

DLFT (Direct Long Fiber Thermoplastic) Thermoset Process:

The process of contacting the fibers and the dispersion may be used in adirect long fiber thermoset process similar to traditional direct longfiber thermoplastic processes. Such a process employs long fibers thatcontacts the dispersion as the fibers in an extruder or other apparatussuitable for pumping the dispersion. In a traditional direct long fiberthermoplastic system (DLFTP), the thermoplastic polymers are generallyheated so that they melt and blend prior to contacting with the fibers.For example, the traditional DLFTP system may employ an extruder intowhich the thermoplastic polymers are introduced through a first opening(e.g., an upstream opening) of the extruder. After melting thethermoplastic polymer, the molten polymer contacts the fibers that areintroduced through a second opening of the extruder in a downstream orfinal section of the extruder. Such a process may be employed inproducing an extruded log having very long, discontinuous fibers. In thetraditional DLFTP system employing thermoplastics, the extruded log isgenerally immediately shuffled to a compression molding press while thethermoplastic is in a molten state (e.g., before any significant heat islost), and molded between a pair of matched mold dies. The dispersionsaccording to the teachings herein enable the use of a DLFTP system witha thermoset resin, and is thus referred to as a DLFTR system. In theDLFTR process, the end product may have long fibers. For example thefiber length may be about 10 mm or more, about 30 mm or more, about 60mm or more, or about 100 mm or more. Prior to the present invention,thermoset resins have not been configured to run in the DLFTP process.The present invention provides a way to run thermoset materials instandard DLFTP extruders and compression molds. In a DLFTR process, adispersion including solid particles having a thermoset resin is fedinto an extruder (e.g., a standard DFLTP extruder). For example, thedispersion may be fed into the first section of the extruder, in thesame location as the thermoplastic materials typically are fed. Thedispersion may advance along the screw of the extruder and contact thefibers in the a downsteam section (e.g. a last section) of the extruderscrew to form an intermediate wet composite material. While in theextruder screw, the intermediate wet composite material may be placedunder a vacuum and/or a sufficient amount of heat may be applied so thatsome or all of the water is removed. For example, a sufficient amount ofwater may be removed so that the composite material is a dry compositematerial prior to exiting the extruder. It will be appreciated that someor all of the drying may occur in a component of the extruder downstreamof the extrusion screw. The material leaving the extruder preferably issufficiently dry so that it can be handled as a solid either immediatelyor after cooling to a temperature at which the solid thermoset resin isa solid. Thus prepared, the dry composite material may be in a shape(e.g., a log or other shape) suitable for placing in a compression mold.It will be appreciated that the process may include a step of cuttingthe dry composite material to a predetermined length, volume, or mass toform a charge for a molding process. The dry composite material (e.g.,the charge) may be placed immediately in a compression mold (e.g., priorto the temperature of the material dropping to room temperature). Here,any residual heat, such as from a drying step, may reduce the heatingand/or time required for curing the thermoset resin in the mold.Alternatively, the process may include a step of cooling the drycomposite material and storing it for later use in a compression moldingprocess. For example, the dry composite material may be cooled to aboutroom temperature prior to a compression molding step. The teachingsherein enables this approach due to the ability to easily add thedispersion (e.g., an epoxy based dispersion) into existing DLFTPextruders for blending it with the fiber reinforcement of choice, andremoving some or all of the excess water, and subsequently compressionmolding a net shape composite.

FIG. 1 is an illustrative polymer emulsion 10. The emulsion includes acontinuous matrix liquid phase 18 and an emulsified phase 14. Theemulsified phase includes a plurality of emulsion particles 12. Theemulsion preferably includes a surfactant 16 that reduces the surfacetension between the two phases, that creates a more stable emulsion, orboth. Preferably the emulsion includes a thermoset resin. The emulsionparticles are generally prepared at a temperature at which the thermosetresin is a liquid. It will be appreciated that an emulsion may be cooledto a temperature at which the thermoset resin becomes a solid so that adispersion of solid particles in the matrix liquid phase 18 is formed.

FIG. 2 is an illustrative graph 20 showing some of the features anddifferences in the behavior of a flowable material that is characterizedas being shear thinning 22′, and a flowable material that has Newtonianflow characteristics 22. Here, a flowable material may be a moltenpolymer, a solution (e.g., a polymer solution), an emulsion, or adispersion of particles. The graphs 20 illustrate the relationshipbetween the apparent viscosity 26 and the shear rate. With reference toFIG. 2, a shear thinning flowable material may have a relatively highapparent viscosity when the viscosity is measured at low shear ratescompared with the apparent viscosity measured at higher shear rates. Ina shear thinning material, as the shear rate increases, the absolutevalue of the first derivative of the apparent viscosity with respect toshear rate decreases and/or the apparent viscosity plateaus to agenerally constant value. In curve for the Newtonian material 22, theapparent viscosity is relatively constant (e.g., compared with a shearthinning material). It will be appreciated that when impregnating fiberswith high concentrations of polymer, it may be advantageous to use amaterial having a generally Newtonian viscosity-shear rate relationshipso that the material easily flows between fibers under these low shearrate regimes.

FIGS. 3A, 3B, and 3C are drawings of illustrative cross-sections atvarious intermediate stages of preparing a pre-molding compositearticle. FIG. 3A illustrates an architecture of fibers 30. Withreference to FIG. 3A, the cross-section is taken at a location where allof the fibers 36 are perpendicular to the plane of the cross-section, sothat only the short dimension (e.g., diameter) of the fibers are shown.It will be appreciated according to the teachings herein, that fibersmay be in any arrangement. For example, they may be aligned uniaxially,aligned biaxally, randomly aligned, aligned randomly in a plane, and thelike. The fibers may be provided as a mat, such as a woven fabric or anon-woven fabric. The architecture of fibers 30 includes spaces 38between the fibers. FIG. 3B is an illustrative cross-section 32 of thefiber architecture 30 after impregnating with a particle dispersion 40.Here, the material may be characterized as a wet composite material. Theparticle dispersion includes a first solid particles 42, a second solidparticle 43 that is different from the first solid particle, dispersedin a carrier liquid 44. The first solid particles 42 preferablyincludes, consists essentially of, or consists entirely of one or morethermoset resins. The second solid particles preferably includes,consists essentially of, or consists entirely of one or more thermosetresins. As illustrated in FIG. 3B, the particle dispersion 40 may fillsome of, substantially all of, or entirely all of the spaces 38 betweenthe fibers 36. FIG. 3C is an illustrative cross-section 34 after a stepof drying the composite material to remove some of, or even all of theliquid from the impregnated particle dispersion. As such, the spacebetween the fibers 38 may include void space 46. The dry compositematerial of FIG. 3C may be characterized by a thickness 48. It will beappreciated that in addition to the thermoset resin, the compositematerials of FIB. 3B and 3C may include additional materials, such asdescribed herein. For example, the materials may include a cross-linkingagent, a cross-linking accelerator, a flow modifier, a cure suppressant,a filler, a colorant, a surfactant, an internal release aid, athermoplastic resin, or any combination thereof.

FIG. 4 is an illustrative cross-section of a consolidated compositematerial 50 after a step of heating the thermoset resin and/or applyinga force to the thermoset resin so that the material is consolidated. Asillustrated in FIG. 4, the thermoset resin 42 may form a continuousphase. Optionally, the second solid particles (e.g., the thermoplasticresin) may form a discrete phase. During the compaction step, the voidsin the dry composite material (see e.g., FIG. 3C) are generally reducedor even eliminated. The thickness 48′ of the consolidated compositematerial is generally less than the thickness 48 of the dry compositematerial.

Prepreg Process:

The process of contacting the fibers and the dispersion may be used inan improved process for preparing a prepreg in which a fiberarchitecture is impregnated with the dispersion. In a typical prepregprocess, the fiber architecture may include bundles of fibers, wovenfibers, nonwoven fibers, stitched fibers, or braided fibers. The fibersmay be in the form of mats. In one traditional method of impregnatingfibers with a thermoset resin, the resin is first cast onto a releasesheet at a known areal density by melting the resin and filming themolten resin onto the sheet with a knife blade type applicator. The filmon the release sheet is then contacted with the fibers. For example, aresin coated release sheet may be brought into contact with the fibersystem, and through several stages of heat and pressure, some or all ofthe resin is transferred from the release sheet to the fiberarchitecture in a process referred to as a “film transfer process”. Analternative process is an “in line impregnation process” where theformulated resin components are impregnated into or applied over thefibers by the use of nip rollers and/or compaction rollers. Since thehardener is typically already added to the thermoset resin before thefilm transfer process or the in line impregnation process, the processmust very carefully control the temperature of the resin and also thetime at that temperature, so that the thermoset resin system does notprematurely cure. In such a traditional approach, the viscosity of thethermoset resin system is generally controlled by heat, cross linking,and fillers. In contrast, a dispersion according to the teachings hereinmay advantageously decouples the viscosity of the system thatimpregnates the fibers from the viscosity of the ingredients of thatsystem (e.g., from the viscosity of the thermoset resins and/or theviscosity of other ingredients in the dispersion particles). Forexample, when the fibers are impregnated with the dispersion, theviscosity of the dispersion is primarily controlled by the viscosity ofthe fluid (e.g., the viscosity of the water) and the impact of theparticles (including the size and concentration of the particles) on thefluid, but is generally not affected by the viscosity of the thermosetresin in the particles. Later, after water is removed, the viscosity ofthe material and other characteristics of the resin matrix will dependprimarily on the viscosity and concentrations of the thermoset resin andother ingredients. Once the dispersion particles (e.g., including thethermoset resin, the curative, and the cure catalyst) are dispersed intothe fibers to form a wet composite material, the wet composite materialmay be dried to remove some or all of the water. The dry compositematerial may be a prepreg suitable for molding and curing into a finalcomposite part.

The process may include a step of blending two or more dispersions. Theprocess may include a step of blending a dispersion and an emulsion. Theprocess may include a step of mixing a water soluble additive with adispersion.

Drying the Wet Composite Material

The process generally requires one or more steps of drying the wetcomposite material for remove some or all of the water. For example thewet composite material may include about 10 wt. % or more water (basedon the total weight of the wet composite material) and there may be aneed to dry the material so that a dry composite material is producedhaving about 2 wt. % or less water (based on the total weight of the drycomposite material). Any method of removing water may be employed. Forexample, the wet composite material may be dried by heating thematerial, by flowing a dry purge gas over the material, by placing thematerial in a desicattor or other low humidity environment, by using avacuum, or any combination thereof. The drying step preferably isselected so that: substantially none of the thermoset material isremoved, so that substantially none of the cross-linking agent isremoved, so that substantially none of the catalyst is removed, or anycombination thereof. A drying step may be performed at a temperature ofabout 120° C. or less, preferably about 110° C. or less, more preferablyabout 100° C. or less, and most preferably about 90° C. or less. When ahigh drying temperature is employed (e.g., from about 100° C. to about120° C.) it may be necessary for the drying time to be short (e.g.,about 1 hour or less, about 20 minutes or less, or about 10 minutes orless). The drying temperature and the drying temperature should besufficiently low so that any curing of the thermoset resin during thedrying step does not substantially affect the ability to form a partusing the dry composite material during a molding step.

The one or more drying steps may remove some of the water, andpreferably removes substantially all of the water in the compositematerial. For example, the drying step(s) may reduce the amount of waterto about 2 wt. % or less, preferably about 1 wt. % or less, morepreferably about 0.5 wt. % or less, even more preferably about 0.2 wt. %or less, and most preferably about 0.1 wt. % or less.

The dry composite material may be employed in a generally high speedmolding operation that employs heat to cure the thermoset material andpressure to shape the dry composite material. Preferred moldingoperations employ a molding temperature of about 100° C. or more, morepreferably about 120° C. or more, even more preferably about 130° C. ormore, even more preferably about 140° C. or more, and most preferablyabout 145° C. or more. The molding temperature is preferably about 210°C. or less, more preferably about 200° C. or less, even more preferablyabout 190° C. or less, even more preferably about 180° C. or less, andmost preferably about 170° C. or less.

The dry composite material preferably has a glass transition temperaturesufficiently high so that the dry composite material generally maintainsits shape during storage. For example, the dry composite material mayhave a glass transition temperature of about 5° C. or more, preferablyabout 10° C. or more, more preferably about 13° C. or more, even morepreferably about 15° C. or more, and most preferably about 17° C. ormore. The dry composite material preferably has a glass transitiontemperature sufficiently low so that the material can be softened andfor shaped in short periods of time. For example the time for softeningand shaping the dry composite material may be about 10 minutes or less,about 3 minutes or less, about 1 minute or less, about 30 seconds orless, or about 20 seconds or less. The softening and shaping time may beabout 2 seconds or more, about 5 seconds or more, or about 10 seconds ormore. The softening and shaping time may be the time from placing thedry composite material in the heated mold to the time the mold isclosed. For example, the dry composite material may have an initialglass transition temperature of about 75° C. or less, preferably about60° C. or less, more preferably about 50° C. or less, even morepreferably about 40° C. or less, even more preferably about 30° C. orless, and most preferably about 22° C. or less.

The process may include one or more steps of preparing a kit thatincludes a plurality of individual pieces of dry composite materials.The pieces may be separate, or may be attached. It will be appreciatedthat the individual pieces of a dry composite material may have the sameshape, may have different shapes, may have the same composition, mayhave different compositions, or any combination thereof. The process mayinclude one or more steps of cutting a dry composite material into apredetermined shape. An attached kit may include a step of adhering orotherwise attaching a dry composite materials to another dry compositematerial. For example, a first dry composite material may be attached toa second dry composite material by heating at least a region of thesurface of at least one of the first or second dry composite materialsto a temperature greater than the glass transition temperature of thethermoset resin. The thermoset resin may be heated to a temperaturesufficient for making at least a portion of the surface tacky. Anysource of energy for heating the surface may be employed. The surfacesmay be contacted before, during or after heating the surface. Afterheating and contacting heating the surfaces, the surfaces may be allowedto cool so that the thermoset resin returns to a solid state. The kit(e.g., the attached kit) may be employed as the pre-molding articleaccording to the teachings herein.

The process may include one or more step of preheating and/or preformingthe dry composite material (e.g., the prepreg) so that the dry compositematerial may easily be placed into a mold. For example, the process mayinclude a step of forming a shaped blank suitable for placing into amold. The preheating step preferably is at a sufficient time andtemperature so that the dry composite material softens. For example, thepreheating temperature preferably is greater than the glass transitiontemperature of the uncured dry composite material. During the preheatingstep, the material preferably is heated to a temperature of about 25°C., or more, more preferably about 35° C. or more, and most preferablyabout 40° C. or more. The preheating temperature and time should besufficiently low so that the dry composite material does notsubstantially cure (e.g., so that the dry composite material is formableat the preheating temperature). For example, the preheating temperaturemay be about 100° C. or less, preferably about 90° C. or less, even morepreferably about 80° C. or less, and most preferably about 70° C. orless. Any suitable heat source may be employed for preheating thematerial. For example, the heat source may include radiant heat,convection heat, or both. The preforming step may include a step ofplacing the material (e.g., the preheated dry composite material) into apreforming tool. Preferably the preforming tool is maintained at atemperature equal to, or less than the glass transition temperature ofthe thermoset resin. For example, the temperature of the preforming toolmay be sufficiently low so that some or all of the thermoset resinsolidifies (i.e., undergoes a liquid to solid phase transition) in thepreforming tool. The preforming step preferably includes a step ofapplying sufficient pressure to the dry composite material (e.g., whileat a temperature above the glass transition temperature of the thermosetresin), so that the material is formed into a predetermined shape. Forexample, the material may be formed into a blank having a shape suitablefor molding into a finished part. The preforming step preferably isperformed using a combination of time and temperature that does notsubstantially advance the curing of the thermoset resin. For example,during the consolidation step, any increase in the glass transitiontemperature of the thermoset resin preferably is about 40° C. or less,more preferably about 20° C. or less, even more preferably about 10° C.or less, and most preferably about 5° C. or less.

The process may include a step of consolidating the dry compositematerial after the drying step and prior to cross-linking the thermosetresin in a cross-linking step. The consolidating process, if employed,may use heat and/or force to increase the bulk density of the drycomposite material. After the consolidating step, the ratio of the bulkdensity of the dry composite material to its theoretical densitypreferably is about 90% or more, more preferably about 95% or more, evenmore preferably about 98% or more, and most preferably about 99% ormore. It will be appreciated that a consolidation step may be part of apreforming step, or may be a separate step. For example, a consolidationstep may be employed prior to a preforming step.

The composite material, prior to molding (e.g., after drying and/orconsolidating), preferably has a long out time. The out time may bedetermined by the time that the material can be stored at a temperatureof about 25° C. without changes in the properties of the material. Forexample, the material may maintain its glass transition temperature(within 5° C.) and/or its drapability during storage. Preferably, thematerial has an out time of about 10 days or more, more preferably about20 days or more, even more preferably about 30 days or more, even morepreferably about 45 days or more, and most preferably about 90 days ormore. The out time may be sufficiently long so that the pre-moldingarticle can be efficiently produced, inventoried, and shipped to amolding facility prior to use.

Molding the Dry Composite Material—Heat Curing/Forming or Shaping

While the dry composite material is in the mold, it rapidly cures andthe glass transition temperature of the thermoset material increases.The glass transition temperature of the thermoset material increasessufficiently so that the molded part can be removed without needing tocool the mold. For example, the molded part may be sufficiently cured sothat it can be removed from the mold (e.g., without deforming the part)in a molding time of about 10 minutes or less, about 7 minutes or less,about 5 minutes or less, about 3 minutes or less, or about 2 minutes orless. The minimum molding time may be about 10 seconds or more, about 20seconds or more or about 30 seconds or more. By eliminating the need tocool the mold for removing the part, fast molding cycle times can beachieved.

During the molding of the dry composite material, the glass transitiontemperature of the thermoset resin increases. By the end of the moldingstep, the glass transition temperature of the thermoset resin issufficiently high so that the cured article is capable of being removedfrom the mold without deforming the article and without substantiallycooling the mold. For example, the process may be free of a step ofcooling the mold by 35° C. or more, preferably free of a step of coolingthe mold by 15° C. or more, and more preferably free of a step ofcooling the mold by 5° C. or more, prior to removing the article fromthe mold.

After curing in the mold, the cured thermoset resin in the compositearticle preferable has a glass transition temperature equal to, orgreater than the molding temperature, and more preferably exceeds themolding temperature by about 5° C. or more. For example, the glasstransition temperature of the thermoset resin after curing may be about120° C. or more, about 125° C. or more, about 130° C. or more, about135° C. or more, about 140° C. or more, about 145° C. or more, about150° C. or more, about 155° C. or more, or about 160° C. or more.

When the dry composite material contacts the mold, the material israpidly heated and the rate of curing soon reaches a maximum. During theone or two minutes starting when the dry composite material contacts theheated mold, the glass transition temperature of the thermoset resinpreferably increases at an average rate of about 4° C./min or more,about 10° C./min or more, about 25° C./min or more, about 40° C./min ormore, about 60° C./min or more, or about 80° C. or more.

The dispersions may be mechanical dispersion. For example, thedispersion may be a mechanical dispersion including a thermoset resinand optionally a cross-linking agent. In particular, the dispersion mayinclude epoxy and an epoxy cross-linking agent (e.g., a hardener). Thedispersion may be prepared using the process described in US PatentApplication Nos: 61/599,062 and 61/599,068, and U.S. Pat. No. 5,539,021,U.S. Pat. No. 5,688,842, and U.S. Pat. No. 6,156,806. The process mayinclude evenly spreading or otherwise uniformly applying the dispersiononto the surface of the fibers (e.g. onto the surface of a woven fibermat) to form a prepreg. The process may include placing the prepreg intoa press or other device suitable for pushing the particles of resin inthe dispersion into the woven fiber architecture. The process mayinclude drying the impregnated material system in an oven to remove thewater. The process may include placing the prepreg in a heated press orother heated mold for a specified amount of time at a predeterminedtemperature for curing the prepreg. The press may be flat plates, whichmay be particularly useful for preparing test specimen for determiningappropriate process conditions. Preferably, the mold is chosen forpreparing a part having a predetermined shape. According to theteachings herein, it may be necessary to build up a kit using aplurality of plys of dry composite material. The process may employ oneor more fixtures for facilitating the building up of a kit. The processmay include a step of cutting pieces of the prepreg for one or more ofthe ply layers. A ply layer may be arranged in a specific orientation.This may be particularly useful when the ply layer has anisotropicproperties. The process may include a step of debulking the kit. Forexample, a step of debulking a kity may include compressing it eitherbetween a matched mold die, or by encasing it in a vacuum bag andapplying a vacuum, with the goal of removing any air or voids betweenindividual layers or between the kit and the fixture. In a debulking orcompressing step, it may be advantageous for the prepreg material to (1)have a certain amount of tack or stickiness, (2) to be able to drape orconform to three dimension surfaces, or both (1) and (2). Advantagously,the use of the dispersion in preparing the prepreg enables the viscosityof the thermoset polymers to be controlled by varying the ratio of solidto liquid epoxy material (e.g., without concerns regarding the abilityto impregnate the fibers). More solid makes a strong final part due tohigher molecular weights in the epoxy. However, more liquid epoxy resincreates tack and also holds the solid epoxy particles in place once thewater is removed from the material in the drying step, before finalcure. Surprisingly, high molecular weight epoxies which are solids atroom temperature may be used (alone, or in combination with liquid epoxyresings) to construct a dispersion that enables the solid particles toremain and the prepreg to still have tackiness and drape before thefinal molding (curing) step.

One or more of the aforementioned steps may be performed in a continuousprocess, such as illustrated in FIG. 5. FIG. 5 illustrates features of asystem that may be employed in producing a pre-molding compositearticle. It will be appreciated that the system in FIG. 5 may includemore, fewer, or different components. For example, the system mayinclude a roll 68 of a fiber containing material 69 (e.g., a roll ofwoven or non-woven fibers). As such, the process for preparing thepre-molding composite article may include a step of unwinding a roll offibers and feeding it between a pair of feed rollers 70. The system mayinclude a roll 66 of a release film 67 for supporting the materialsduring processing and/or for separating layers of the compositematerial. The release film 67 may contact the fiber material 69 at thefeed rollers 70. The system may include dispersion dispensing device 62for dispensing the particle dispersion 40. The dispersion dispensingdevice 62 preferably dispenses the dispersion 40 at a uniform rate, at auniform thickness, or both. The system may include a heater 64, avacuum, or both for removing some or all of the carrier liquid 80 (e.g.,moisture) from the dispersion. The system may include a set of rollers(not shown in FIG. 5) between the dispenser 62 and the heater 64 toaccelerate the flow of the dispersion 40 into the spaces between thefibers. The system may include a set of compression rollers 72. Thecompression rollers 72 may be used for applying an upper release film 75above the materials and/or for compressing the composite material toremove some or all of the voids. The system may include a roll 74 forsupplying the upper release film 75. The system may include one or moresets of take-up rollers 76 for guiding the composite material onto aroll. 78. It will be appreciated that an early stage, the materials maybe characterized as a fiber material with the dispersion generally ontop of the fibers 82. At a later stage, the materials may becharacterized as fibers impregnated with some or all of the constituentsof the dispersion (e.g., with the carrier liquid or without the carrierliquid) 84.

The pre-molding articles according to the teachings herein may beemployed for molded parts having a range of geometries. The shortmolding cycle times achievable by employing the particles dispersionsmakes the materials particularly attractive for high volume parts. Forexample, the pre-molding articles may be used for production ofautomotive parts, particularly where the prior methods of preparingthermoset-fiber composites have proven to be costly. It will beappreciated that the particle dispersions according to the teachingsherein may also be employed in laminate applications, in injectionmolding applications by preparing pellets suitable for injectionmolding, and other industrial composite applications. A 3-dimensionalmolded component (e.g., having varying thickness) can be prepared bycompression molding a pre-molding article, by using the dispersion forpreparing a sheet molding compound, or by preparing injection moldablepellets.

Test Methods

The glass transition temperature of a polymer (e.g., a thermoset resin)or a polymer composition that is free of fibers may be measured usingdifferential scanning calorimetry according to ASTM D7426-08. Themelting temperature and/or crystallinity of a polymer (e.g.,thermoplastic polymer) may be measured using differential scanningcalorimetry (DSC), according to ASTM D 3418.03.

EXAMPLES Dispersion Example A: Preparation of Thermoplastic Dispersion

A polyester dispersion is prepared using a polyester that is dispersiblein sulfonated water. CADENCE™ GS2 brand polyethylene terephthalatecopolymer polyester (commercially available from Eastman Chemical) isused. These polyesters have very little solubility in common organicsolvents and have high viscosity. Thus, it is difficult to prepare fiberreinforced composite materials containing these polyesters usingtraditional melt processes or using traditional solution processes.Example A thermoplastic dispersion is prepared in a twin screw extruder.The polyester is fed into the extruder using a loss in weight feeder.Eastman AQ 55s sulfonated water (commercially available from EastmanChemical) is used as the dispersant. It will be appreciated that othersurfactants and/or other thermoplastic polymers may be employed. Thesulfonated water is fed into the twin screw extruder using a volumetricfeeder. During start-up, the barrel temperatures are set to about 160°C. to ensure that the polymer melts and to prevent over torqueing of theextruder. The barrel temperatures are then reduced to about 140° C. Thesulfonated water was preheated to about 130° C. The sulfonated water isfed into the extruder at a position where the thermoplastic is molten.The screw speed is sufficiently high so that polyester particles areformed. Following the dispersion zone, a diluent is added. The diluentis deionized water. The diluent stream is preheated to about 120° C.

The Example A thermoplastic dispersion is expected to have theproperties shown in Table 1:

TABLE 1 Properties of the Dispersion Example A Property ValueConcentration of polyester (% of solids) ≧95 weight percent PercentSolids ≧50 weight percent Viscosity (RV4, 50 rpm) ≦5,000 poise AverageParticle Size, Vmean ≦1 μm

Dispersion Example B: Preparation of High MW Epoxy Resin Dispersion

A particle dispersion including a solid thermoset resin is prepared asfollows. The thermoset resin is D.E.R.™ 6155 solid epoxy polymer,commercially available from The Dow Chemical Company. The resin has anepoxide equivalent weight of about 1250-1400 g/eq (as measured accordingto ASTM D-1652), and a melt viscosity of about 40,000-55,000 cSt at 150°C. (as measured according to ASTM D-445). The resin has is a reactionproduct of epichlorohydrin and bisphenol A, and has a softening point ofabout 105-125° C. (as measured according to ASTM D-3104). The thermosetresin is fed into a twin screw extruder by means of a feeder suitablefor feeding solid materials. The extruder melt zones are set at about140° C. An initial stream of deionized water (IA) is fed into polymermelt. A surfactant solution (60% active) including E-SPERSE 100 (60%active), commercially available from Ethox Chemicals LLC is also fedinto the extruder. E-SPERSE 100 is a water soluble anionic surfactant.The surfactant may be fed at the polymer melt, may be fed along with theIA or may be fed after the IA. A heated dilution stream of deionizedwater is introduced into the extruder at a downstream zone, followingthe formation of the thermoset particles in the dispersion zone toobtain a dispersion. The dispersion is filtered through using a filterhaving a pore size of about 190 micron pore size filters. The resultingdispersion is stable and has the following properties illustrated inTABLE 2.

TABLE 2 Properties of the Dispersion Example B Property ValueConcentration of D.E.R. ™ 6155 (% of solids) 95 weight percentConcentration of E-SPERSE 100 (% of solids) 5.0 weight percent pH 5.74Percent Solids (as measured using IR) 62.4% Viscosity (RV4, 50 rpm) 1246cPoise Average Particle Size, Vmean 0.409 μm Top particle size, D < 900.560 μm

Particle size is measured on diluted samples (diluted in DI water) witha Beckman Coulter LS 13 320 light-scattering analyzer. An epoxy opticalmodel is used for analysis. The pH of the dispersion is measured using aDenver Instruments pH meter. The solids analysis is measured using a CEMLabWave 9000 microwave solids analyzer at 70% power. Viscosity ismeasured on a Brookfield rotational viscometer at the stated conditions.

Dispersion Example C

Technicure D-5 is a dicyandiamide based epoxy curing agent commerciallyavailable from AC catalysts, Inc. A suspension (dispersion) ofTechnicure D-5 is prepared by adding 10 g of deionized water to 2 g ofTechnicure D-5 powder and subsequent mixing on a vertex mixer for about1 minute.

Dispersion Example D

Dispersion Example D is a mixture of Dispersion Example B and DispersionExample C. Example D is prepared by mixing about 20 g of the epoxydispersion and about 4.3 g of the Technicure dispersion. The twodispersions are mixed using a dual axes mixer for about 2 minutes at3000 rpm.

Dispersion Example E

Dispersion Example E is a hybrid thermoset-thermplastic dispersion(i.e., a blend dispersion). Dispersion Example E is prepared by mixingDispersion Example A and dispersion Example D. About 50 weight % of eachof dispersion A and dispersion D (based on the weight of the solids ofthe dispersions) are mixed using a dual axis mixer for about 2 minutesat a speed of about 3000 rpm.

Dispersion Example F

Dispersion Example F is a polyolefin dispersion prepared from anethylene/1-octene copolymer having an octene concentration of about 38weight percent, a melt index of about 5 g/10 min (measured according toASTM D1238 at 190° C./2.16 kg), and a melting temperature of about 63°C. (measured using differential scanning calorimetry at 10° C./min). Thedispersion is prepared in a twin screw extruder at a temperature ofabout 150° C. A 26 carboxylic acid (UNICID 350 commercially availablefrom Baker-Petrolite and having an acid value of about 115 mg KOH/g) isused as a surfactant for the copolymer particles, at a concentration ofabout 3.1 parts per 100 parts of copolymer. An aqueous solution ofpotassium hydroxide is fed into a downstream section of the extruder tocreate the dispersion of the copolymer in the water. Additional water isadded further downstream in the extruder to dilute the dispersion. Theresulting dispersion has a solids content of about 56 percent by weight,a pH of about 10.6, and an average diameter of about 0.79 μm. Greaterthan 95 weight percent of the solids is the copolymer.

Dispersion Example G

Dispersion Example G is a hybrid thermoset-thermplastic dispersion(i.e., a blend dispersion). Dispersion Example G is prepared by mixingDispersion Example F and dispersion Example D. About 50 weight % of eachof dispersion F and dispersion D (based on the weight of the solids ofthe dispersions) are mixed using a dual axis mixer for about 2 minutesat a speed of about 3000 rpm.

Dispersion Example H

Dispersion Example H is a hybrid thermoset-thermplastic dispersion(i.e., a blend dispersion). Dispersion Example H is prepared by mixingdispersion Example D with a dispersion of polyamide 6. The polyamide 6dispersion is an aqueous dispersion including about about 50 percentsolids content and an average particle diameter of less than 1 μm. About50 weight % of each of the polyamide 6 dispersion and dispersion D(based on the weight of the solids of the dispersions) are mixed using adual axis mixer for about 2 minutes at a speed of about 3000 rpm.

Composite Example 1

Composite Example 1 is prepared using Dispersion Example A. DispersionExample A is applied to a carbon fiber mat by immersing the fiber matinto a bath containing the dispersion. After immersing the mat with thedispersion, the composite material is partially dried in air. Afterpartially drying in air, the mat is again immersed in the dispersionbath so that additional dispersion can be applied. This process isrepeated two more times so that the mat contains a sufficient amount ofthe dispersion. After achieving a desired concentration of dispersionparticles, the wet composite material is dried in an oven. The materialis initially dried at 90° C. for 3 hours and then at 160° C. for anadditional 30 minutes.

Composite Example 2

Composite Example 2 is prepared using Dispersion Example E. DispersionExample E is applied to a carbon fiber mat by immersing the fiber matinto a bath containing the thermoplastic-thermoset hybrid dispersion.After immersing the mat with the dispersion, the composite material ispartially dried in air. After partially drying in air, the mat is againimmersed in the dispersion bath so that additional dispersion can beapplied. This process is repeated two more times so that the matcontains a sufficient amount of the dispersion. After achieving adesired concentration of dispersion particles, the wet compositematerial is dried in an oven. The material is initially dried at 80° C.for 1 hour.

The material does not cure during the drying conditions and can bemolded and cured in a subsequent process. The material is tack free andcan easily be handled. For example it can be lifted, moved andpositioned by mechanical means.

The dry composite material is then cured by heating the material to 180°C. for 30 minutes. During the curing the glass transition temperature ofthe epoxy resin increases by about 30° C. or more. The cured materialhas a sufficient glass transition temperature so that it maintains itshape when removed from the curing oven without cooling the oven.

Composite Example 3

Composite Example 3 is prepared, dried, and cured as described above forComposite Example 2, except Dispersion Example G is used instead ofDispersion Example E. During the curing the glass transition temperatureof the epoxy resin increases by about 30° C. or more. The cured materialhas a sufficient glass transition temperature so that it maintains itshape when removed from the curing oven without cooling the oven.

Composite Example 4

Composite Example 4 is prepared, dried, and cured as described above forComposite Example 2, except Dispersion Example H is used instead ofDispersion Example E. During the curing the glass transition temperatureof the epoxy resin increases by about 30° C. or more. The cured materialhas a sufficient glass transition temperature so that it maintains itshape when removed from the curing oven without cooling the oven.

1. A pre-molding article comprising i) a polymer phase including one or more thermoset resins, one or more thermoplastic resins, and one or more cross-linking agent suitable for cross-linking the thermoset resin; and ii) an inorganic phase, wherein the inorganic phase is present at a concentration of about 30 volume percent or more based on the total volume of the polymer phase and the inorganic phase; wherein the polymer phase is a continuous phase; and the weight ratio of the one or more thermoset resins to the one or more thermoplastic resins is about 0.1 or more.
 2. The pre-molding article of claim 1, wherein one of the thermoset resins has an initial glass transition temperature, T_(gi), and one of the thermoplastic resins has a peak melting temperature, T_(p), wherein T_(gi) is less than T_(p).
 3. The pre-molding article of claim 2, wherein the cross-linking agent is present at a concentration sufficiently high so that upon curing, the glass transition temperature of the thermoset resin is increased to T_(gc), wherein T_(gc) is greater than T_(p).
 4. The pre-molding article of claim 1, wherein the cross-linking agent is encapsulated.
 5. The article of claim 1, wherein the inorganic includes fibers, selected from woven fibers, fiber particles, unidirectional fibers, fiber mats, or any combination thereof.
 6. The pre-molding article of claim 1, wherein the polymer phase includes thermoset resin domains having at least 70% by volume thermoset resin and thermoplastic resin domains having at least 70% by volume thermoplastic resin. 